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Rules for deciding the number of significant figures in a measured quantity: (1) All nonzero digits are significant: 1.234 g has 4 significant figures, 1.2 g has 2 significant figures. (2) Zeroes between nonzero digits are significant: 1002 kg has 4 significant figures, 3.07 mL has 3 significant figures.
Use the order of mathematical operations to determine which order to apply the rules for addition/subtraction (determine the number of sig figs for that step) or the rules for multiplication/division.
There are three rules on determining how many significant figures are in a number: Non-zero digits are always significant. Any zeros between two significant digits are significant. A final zero or trailing zeros in the decimal portion ONLY are significant. Focus on these rules and learn them well.
Significant Figures - Rules. Significant figures give the reader an idea of how well you could actually measure/report your data. ALL non-zero numbers (1, 2, 3, 4, 5, 6, 7, 8, 9) are ALWAYS significant. ALL zeroes between non-zero numbers are ALWAYS significant.
Significant Figure Rules. You can navigate to specific sections of this handout by clicking the links below. Determining Number of Significant Figures (Sig Figs): pg. 1. Addition/Subtraction: pg. 2. Multiplication/Division: pg. 2. Conversions: pg. 3. Sample Problems: pg. 4. Determining Number of Significant Figures (Sig Figs) .
In much of scientific work the “±” notation is dropped, with the understanding that in the measurement “2.234 g” the last digit has some uncertainty. All digits in a measured quantity (mass, length, volume, temperature etc), including the uncertain one, are called significant figures.
The significant figure rules are outlined below. We will apply these significant figure rules in all subsequent lab reports, in General Chemistry lecture courses on exams and homework and in all subsequent problems in your chemistry courses in both laboratory and lecture.
